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A comment on China's version of GPS now has more satellites than US original. Parent comment

Re:China's version of GPS now has more satellites than US or... by raihansaputra on Tuesday August 20, 2019 @06:42AM (#20745416)
The US is able to block GPS signal to a specific area (I think it was done on the Gulf War) or disable the unencrypted GPS signal (only the US military can decode them). I assume each system has the same capability too. The worst case scenario would be all parties decided to block the unencrypted portion and leaving all civilians to be location-blind, including civilian aircrafts.
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Re:China's version of GPS now has more satellites than US or... by throw0101a on Tuesday August 20, 2019 @08:00AM (#20745891)
> The US is able to block GPS signal to a specific area ...

Anyone can block the signal given how weak it is, and there are news reports of people doing so (and being charged for it). You can supposedly buy jammers online for not a lot of money.

> ... (I think it was done on the Gulf War) or disable the unencrypted GPS signal (only the US military can decode them).

What you are probably referring to is "Selective Availability" and is the purposeful degrading of the signal to make it less accuracy. The DoD said it will not do so, and has given assurances to the FAA (because planes are now highly dependent on it). The newest GPS III satellites no longer have the S/A hardware:

* https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_...

By 2000 people had figured out to get quite accurate results even with the S/A enabled, so the whole thing not as useful:

* https://www.aviationtoday.com/2000/07/01/the-real-reason-sel...

If there's a war on it's probably cheaper to just jam in the area of operations.

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Re:China's version of GPS now has more satellites than US or... by tyldum on Tuesday August 20, 2019 @04:39PM (#20751841)
Jammers are cheap and since a lot of expensive gear has GPS tracking these days, thieves are using simple jammers you plug into the cigarette outlet in cars. This is increasingly becoming a larger problem since they jam a relatively large area.
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Re:China's version of GPS now has more satellites than US or... by jhayward on Tuesday August 20, 2019 @08:09AM (#20745956)
> The US is able to block GPS signal to a specific area

The GPS system does not have any area denial capability. If the US wants to block it in a certain area they have to deploy terrestrial jammers just like anyone else.

Allies get decryption keys for the military high-accuracy signal.

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